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By D. A. Fenton

The structural design of large grinding mills, with reference to shell-mounted bearings by D. A. FENTON*, P. Eng. (Visitor) The paper outlines the advantages of shell-mounted grinding mills over mills having a conventional trunnionsupported shell. The growing use of larger mills in the past decade has led to a significant number of mechanical and structural failures, the most common being those at the junction of the head and the shell. Larger mill diameters favour the use of shell-mounted bearings. The elimination of castings, which have an inherent weakness to fracture, makes the shell-supported mill lighter and stronger than a conventional mill of the same shell thickness.

Jan 9, 1976

The increasing transportation of solids by pipeline, in South Africa and internationally, replacing the conventional transportation methods of rail, road, and conveyors, has resulted in much research into this area of solids transportation. Pipeline wear continues to be an area of specific concern, since it constitutes a major cost during the life of a pipeline installation. Wear data from an accelerated wear test and actual pipeline tests are presented. Trends in the performance of the pipeline materials tested are discussed, and possible solutions to the problem of pipeline wear are presented.

Jan 1, 1992

By B. J. Ralph, I. J. Corrans, B. Harris

In the first section, a brief background to the practical and theoretical aspects of bacterial leaching is presented. Descriptions are given of present and potential methods for exploiting bacterial leaching in metal-winning. In the second section, the results of recent research are presented. The aim of this work was to obtain a greater understanding of the mechanism of bacterial leaching of sulphide minerals. Bacteria were observed to catalyse leaching reactions by oxidising ferrous ions to ferric ions, by removing protective films at the mineral surface and by depolarising cathodic areas.

By D. E. Scheck

A computer-aided blast design consultant system has been developed. The software consists of two modules: one uses theoretical and empirical formulae and procedures to design a blast based on user supplied geological and mechanical data, while the other is an expert system that analyzes blast vibration problems and recommends remedial action using knowledge based rules. The system is currently undergoing field evaluation.

Jan 1, 1987

By V. H. R. Brereton

The gold deposits of the farms Lisbon and Berlyn in the Eastern Transvaal by V. C. H. R. BRERETON* (Visitor) This paper describes the discovery and recovery of gold, over a period dating back to the 1870s. on the farms Lisbon and Berlyn, situated approxim ately 1I km north-east of Pilgrims Rest. where mining ceased in July 1971. 99 years after gold was first discovered in the Pilgrims Rest and Sabie districts. Included in the paper are accounts of the discovery and mining operations of the Lisbon-Berlyn Company from 1884 to 1890. The operations of small companies and syndicates. the superficial winning of gold by diggers, and the encouraging reports of four mining engineers in 1890 are also mentioned.

Jan 11, 1973

By H. E. Cross

Metallurgical considerations in the automation of gold-recovery plants By H. E. CROSS. Pr. Eng., B.Sc. (Eng.) Hons. (Fellow) The advantages of the automation of gold-recovery plants are examined. The various sections of a gold-recovery plant are analysed, and the extent to which instrumentation can usefully be employed is described. INTRODUCTION The scope of this paper is restricted to the ore-treatment and recovery plants on Witwatersrand gold mines. To extend the field to plants that process base metals and industrial minerals would result in a paper that would be too lengthy. However, the subject matter of this paper is applicable to most mineraldressing and recovery plants and will, it is hoped, be a foundation on which to build somewhat more sophisticated control systems required in the base-metals field.

By Peter Smith

The construction of one of the world's largest goldrecovery plants to treat run-of-mine ore is progressing on schedule at the President Brand Gold Mine in the Orange Free State. Designed to treat 390 kt per month, the plant will recover 96 per cent of the gold from the ore at a capital cost of 160 million rands in terms of January 1983 money. It will replace the existing gold-treatment installation, as well as provide a 30 per cent increase in capacity. Mintek reports Report M161 Improved recoveries of gold from auriferous calcines and pyrites by fine milling. Report M171 The development of a versatile computer programme for the evaluation of batchflotation results. Report M178 The reduction of chromite in a transferred-arc plasma furnace. Report M179 Optimization of an inductively coupled plasma by the simplex method.

Jan 1, 1985

With the increased variability of today's large-scale mining operations, consistent flotation performance is important to improving and sustaining overall recovery through the circuit. The Newcrest Telfer Mine has implemented advanced process control technology to obtain stable level operation and consistent mass pull in the copper rougher and scavenger flotation circuits. The final result has been an overall reduction in variability, which impacts on both copper and gold recovery. This paper describes the methodology and implementation of the improvements in control at the Newcrest Telfer Mine as being an essential part of the business for minerals processing.

Jan 1, 2007

By A. O. Filmer

An account is given of a study on the non-oxidative dissolution in aqueous acidic solutions of nickel sulphides of different stoichiometric composition, in which a rotating ring-disc electrode was used. The rate of dissolution was found to depend on the potential of the sulphide and the nickel-to-sulphur stoichiometric ratio. A maximum rate for the dissolution of nickel from nickel sulphides containing an excess of nickel was recorded at potentials around -0,2 to -O,3V. The rate decreased markedly at more anodic potentials. For nickel-deficient nickel sulphides, the nonoxidative dissolution rate increased with a cathodic shift in potential. Under open-circuit conditions, a nickel sulphide of a composition approximating Ni ,S. reacted most rapidly. The dissolution rate was controlled by either a chemical or an electrochemical reaction at the electrode surface, had an activation energy of between 50 and 65 kJ.mol-1, and was independent of stirring speed.

Jan 1, 1980

By J. A. L. Napier

By use of a functional model of capital expenditure developed earlier, a prototype cash-flow model is formulated as a basis for the investigation of the economic consequences when the production rate of a mine is manipulated as fundamental design variable. The optimum production capacities that maximize the common economic criteria of net present value, present-value ratio, and wealth growth rate are determined. It is shown that these choices depend certain key groupings of the economic parameters, and that they have a fixed interrelationship. The basic cash-flow model is extended further to include the effects of a constrained rate of production buildup and the imposition of State taxation on generated income. An approximation to the initial tax-free period of a new mining venture is developed, and, by use of these results, the optimum choice of production level is analysed when both the buildup rate is constrained and tax is imposed. This extended model permits a comparison between the performance of existing mines and the predicted theoretical production levels for these mines.

Jan 1, 1981

A brief overview is given of the issues regarding the processing of waste electrical and electronic equipment (WEEE). The printed circuit board component of WEEE is an exceptionally complex feed to possible recycling processes. Scrap printed circuit boards were selectively smelted at 1 200°C to produce a metallic alloy. Iron and aluminium were found not to be part of the alloy. The alloy was characterized by SEM-EDS, and three phases were identified: alpha and delta bronzes, and a lead-rich phase. Calculations show that about 56 mass per cent of the alloy is the alpha phase, 35 per cent delta phase and 9 per cent lead phase. A simplified approach using appropriate binary phase diagrams was used to derive a phase composition for the alloy. This was further backed by FactSage calculations, which showed that the simplified approach was appropriate for this alloy. The experimental findings and theory were found to agree well.

Jan 1, 2009

By S. Vorberg, B. Fischer, U. Glatzel, R. Völkl, D. Lupton, M. Wenderoth

Owing to their excellent oxidation and corrosion resistance, Pt and its alloys are being used preferentially at elevated temperatures and in aggressive environments. For example, an important application field is the glass industry. Alongside the discovery of new potential application fields, the knowledge of material properties is essential for computer simulations, design configuration, process optimization, research and development or quality assurance purposes. Due to the importance for technical applications high-temperature properties have been investigated for currently available Pt-base alloys with ongoing improvements. For the determination of tensile creep test data up to 3000°C, including precise strain measurement, special experimental equipment has been developed at the University of Applied Sciences Jena, Germany. An overview of the existing and newly obtained mechanical property data on pure Pt, solid-solution strengthened Pt-Rh alloy, oxide dispersion-hardened materials Pt DPH and Pt 10%RhDPH as well as cutting-edge results on Pt-base superalloys hardened by intermetallic precipitates will be presented and discussed. Furthermore, some important application examples for the abovementioned Pt-materials will be given.

Jan 1, 2006

Mr R.D. Beck attended Felsted School in Essex (England) and the Royal School of Mines, University of London, where he ob¬tained the degree of B.Sc.(Eng.), A.R.S.M. in mineral technology in 1969. His other qualifications include Pr.Eng. (1976), C.Eng (1975), and M.I.M.M. (1975). He joined Gold Fields of South Africa in December 1969, and worked at Doornfontein Gold Mine, Greenside Colliery, West Driefontein Gold Mine, Zwartkloof Fluorspar, Gold Fields Laboratories, Gold Fields Head Office, Libanon Gold Mine, and Kloof Gold Mine before being appointed Plant Superintendent at East Driefontein Gold Mine in January 1973. In June 1976, he was transferred to Head Office as Group Metallurgist, followed, in November 1978, by his secondment to Black Mountain Mineral Development Company as Plant Superintendent, to take on-site responsibilities for staff training, plant commissioning, and start up. On his return to Head Office in July 1980 as Assistant Consulting Metallurgist, he was responsible for Black Mountain and new metallurgical projects. Then, in January 1984, he was appointed General Manager of the Zinc Corporation of South Africa Limited. He became a member of The South African Institute of Mining and Metallurgy in 1973.

Jan 1, 1985

By C. Mueller

In many automated mines, multi media video and audio funtionality has to be combined with sensor information or steering commands, which is the idea of a new, PC based integrated and multi media capable control system. The new control system (Multimedia Control - MMC) bases entirely on TCP/IP networking and internet technology. For the first time, this enables the ‘intelligent’ use of video and audio information: pictures and voice sequences may be forwarded on request only, they may be stored if particular events occur (e.g. video black boxes) and sensor signals as well as actions from the automation system can directly be assigned with multi media sequences. MultiMedia Control entirely bases on object oriented software. It uses most modern software technology. As user interface, only a standard web browser is required. This makes the handling of different machines easy. By using mobile web pads, dedicated local operator interfaces are not required any longer. The service staff just connects to the automated equipment by – wireless –LAN to make required adjustments. Customization is easy using an open Application Programming Interface. Software modules may be added to the system without touching or recompiling existing components. The system was prototyped in 2000 using a demo-application. The performance tests showed very positive results both regarding the control system behaviour and the speed/latency timing behaviour of the multi-media information processed. The system now is slightly reshaped to completely meet the final product requirements. It is expected to be available by the end of 2001. Key words: Machine Automation; Control System; Multi Media; Remote Control; Teleoperation; Ethernet; TCP/IP; Internet Technology; Streaming Video; Quality Assurance; Service; Control Centre.

Sep 1, 2001

An evaluation was made of the wear and performance characteristics of liter bars, and the cost-life effectiveness of backing materials for rotary-mil liners. In a large run-of-mine mil in which the liter bars were mounted on grid liners of austenitic manganese steel (AMS), the liners had an average life that was five to six times that of equivalent unprotected liners. For a single mil, this is equivalent to annual savings in the cost of materials of up to R320 000, and to a downtime of 100 hours. Of the five materials tested in a large pebble mil grinding quartzitic ore, AMS grids and 'white iron' blocks performed best on a cost-life basis, with possibly improved performance from a real white cast iron. (The 'white iron' was shown by microstructural analysis to contain flake raphite and pearlite, being in reality a grey cast iron.) The high-chromium white iron had by far the longest predicted life, with mild steel a surprising second. Rubber was shown to last well in this type of mil. The wear rates of liners change during their lifetimes. The protective effect of liter bars was clearly illustrated by the reduction of over 40 per cent in the wear rates of the liners when the lifter bars were renewed to a height of 80 mm from a fully worn height of 35 mm.

Jan 1, 1991

By S. M. Bradshaw

In order to assess the requirements for online matching when using a transverse electric field (E-field) applicator to treat mineral ores continuously, the effect of varying load properties on matching has been investigated by simulation. The effective permittivity of the ore to be treated is expected to show variation on both short (< 1 s ) and long (minutes) time scales. By modelling the ore as a series of slices with alternating effective permittivity values, it was shown that permittivity variations on the scale of the expected particle size are attenuated significantly and matching is not required. For variations in permittivity on the length scale of the free-space wavelength, variations in reflected power are at most within ±10% of the mean. This is not considered operationally significant, as extreme permittivity variation over this length scale is unlikely, given the expected distribution of ore particle sizes to be treated. At typical ore transport speeds through the applicator, these variations occur on a time scale an order of magnitude shorter than the response time of typical industrial online matching equipment. This implies that online matching is neither required nor possible for short time scale variation. Long-term variations in dielectric properties can be adequately compensated for by current matching technologies. It is concluded that the transverse E-field applicator is robust to changes in the dielectric properties of crushed ores within the expected range of their variation.

Jan 1, 2012

By L. Marais, S. Denoon-Stevens, J. Cloete

"Historically, mining companies worldwide provided housing and developed towns to accommodate their employees. At the end of the 1980s this approach became less prevalent and attempts were made to mitigate the effects of mine development and mine closure on communities living near the mines. Permanent settlement in mining towns urgently needed to be minimized. Since the advent of democracy, South African policy has moved in the opposite direction, shifting the emphasis to creating integrated communities and encouraging home ownership. Despite this policy shift, however, mines continue to influence local housing conditions. One direct outcome has been the development of informal settlements. We surveyed 260 informal settlement households in Postmasburg, a small and remotely located town in the Northern Cape Province of South Africa. We found that because they employ contract workers and thus arouse expectations of employment, the mines here contribute extensively to the development of informal settlements. But local factors also contribute, and the functional role of informal settlements as a form of housing that supports mobility should not be underestimated. We also found that both municipal and mining company policies for informal settlements were inadequate. Finally, we found that low-income informal settlers not associated with mine employment suffered the highest levels of social disruption.IntroductionA mine generates demand for labour, which in turn generates demand for housing. When settlements spring up near a mine this often means poor housing conditions. In South Africa in the 1960s and 1970s mining companies invested heavily in company towns or mining settlements, but they have become increasingly hesitant to do so, for three reasons. First, declining resource prices in the mid-1980s and the 1990s compelled them to focus on core business interests and reduce the costs of peripheral activities such as housing (Bryceson and MacKinnon, 2013); second, at the turn of the 20th century they were often accused of taking over the role of local government (IIED, 2002) and consequently became hesitant to invest in developing mining towns; and third, changing labour regimes also curbed their investment in such towns (Haslam McKenzie, 2010). Increasingly, the companies began to endorse block-roster shifts, and outsourcing also became more common in the early 1990s. Block-roster shifts in Australia (together with improved technology) have meant that miners do not need to settle near the mines but can fly in and fly out and have their urban houses as their stable homes. This has had serious negative implications for housing in remote towns in Australia, particularly worker camps, large-scale renting out of available accommodation, and ‘hot-bedding’."

Oct 1, 2018

By C. Fiore, A. Kok, W. C. Coningsby

Quarrying is a comparatively simple process which is open to certain economic pitfalls, One of these is the appropriate size of the equipment needed to meet demand.

Jul 1, 1970

NIM Reports Report No. 1647 The industrial application of KEGOLD electrodes. Report No. 1665 The determination of minor amounts of antimony in ores and concentrates by atomic absorption spectrophotometry.

Jan 1, 1975

Letter to the Editor With reference to the recent questionnaire in the December 1980 issue on &apos;The Contents of Journals&apos;, I have made the following observations.

Jan 1, 1981